The pipeline is of a type having a connection end with a deformed annular bead, comprising a connection stub and a screw-connection coupling part, which can be screw-connected to the connection stub in order to retain the pipeline in a sealed manner. The connection stub has an accommodating opening with a radial step surface for axially supporting an end surface of the pipeline and with an inner cone which widens outward away from the step surface. The pipeline may be clamped-in, by way of the annular bead, with a form fit between the connection stub and a supporting ring, which is seated on the pipeline between the annular bead and the screw-connection part.
Numerous configurations of pipe screw-connections for connecting prefabricated pipelines each having an annular bead formed by an upsetting operation are known. Examples include the following publications: DE 195 20 099 C2, DE 195 26 316 C2, and EP 1 054 203 A1. The main disadvantage with such pipe screw-connections is that, during assembly, by virtue of the screw-connection part (coupling nut) being screw-connected, the pipe tends to rotate in unison. In the case of two similar pipe screw-connections according to DE 195 11 063 C2 and DD 240 059 A1, the pipe is clamped in via two cone surfaces in the region of the deformed annular bead between the stub and coupling nut. In the case of the known arrangements, the pipe tends to rupture immediately behind the annular bead when subjected to dynamic loading.
EP 0 926 415 A1 discloses a pipe screw-connection (pipe connection) of the generic type described in the introduction. Provided in this case in order to avoid the pipe rotating along in unison is a supporting ring or a supporting sleeve which is seated on an axis-parallel pipe section between the coupling nut and the deformed annular bead and, with the annular bead, forms an abutment surface which is to be at an angle of between 15° and 40° to the pipe or screw-connection axis. In particular a radial abutment surface, i.e. one running at right angles to the axis, is to be formed in the direction of the coupling nut; alternatively, there may also be cone abutment in this region, in an inner cone of the coupling nut, at an angle of between 45° and 70° to the pipe axis. It has been found that it is also the case that this known pipe connection of the generic type still does not rule out to a sufficiently reliable extent the situation where the pipe rotates along in unison during the screw-connection assembly. Moreover, there is also a fairly high risk of rupturing in the region of the clamped-in annular pipe bead.
DE 197 42 917 C1 describes a further similar pipe screw-connection, the pipe being retained in a clamped-in state, by way of the annular bead, likewise in a conical surface of a separate supporting ring. In this case, however, the supporting ring is supported, on the one hand, on the coupling nut and, one the other hand, on the radial end surface of the connection stub, this giving rise to a rigid limitation to tightening.